its REALLY simple..originally its of ten lines...bit i truncated two lines in here as i feel they would have made it (REALLY)raised to 10, simple 😛...they can however be revealed for further clues if need be :)just wish to clarify...the answer could be anything...being..object..spell..book...so broaden ur perspectives..but rest assured ONLY one answer would meet all the clues.. 😆and one more thing.."coal" is used metaphorically..not literally...You may feel I sound like one rodent,
though in-principle I do meet its characteristic.
I set out on a quest to find the strongest coal,
hoping to illuminate and fuel my goal.
Success I accomplished so I felt,
but slowly, reality hit me with a pelt.
I realised I was crying and drowning,
as the devil inside was rapidly breeding.
My services culminated in my brutal end,
a pain so terrible by a foal which master did not apprehend.
P.S. - The two truncated lines are now revealed... happy guessing 😊